1. Field of the Invention
The present invention relates to digital audio broadcasting (DAB), and more particularly, to a method and apparatus of providing and receiving video services in DAB.
2. Description of the Related Art
Analog audio broadcasting has drawbacks in that signal quality is remarkably deteriorated while a receiver is moving, power efficiency is poor due to high power used for removing noise, and spectrum efficiency is low since different frequencies are used in adjacent regions to avoid channel interference. To eliminate these drawbacks, studies into Digital Audio Broadcasting (DAB) that can substitute for existing analog radio broadcasting such as AM, FM radio broadcasting, are currently underway. A standard for such digital audio broadcasting is disclosed in ‘ETSI EN 300 401’ issued by ETSI (European Telecommunication Standardization Institute).
The standard ‘ETSI EN 300 401’ is also called ‘EUREKA-147’. The ‘EUREKA-147’ describes providing of audio services and various additional services with CD-level quality using a superior audio compression technique based on MPEG-1 audio layer II at a band width of about 2 MHz. In order to transmit a large amount of audio data and general data at an optimal data rate using a limited band-width under a given channel environment, audio data are error-corrected by UEP (Unequal Error Protection) and general data are error-corrected by EEP (Equal Error Protection).
DAB is a type of multimedia broadcasting in which high-quality multi-channel audio is transmitted and various types of additional data are provided. The additional data includes still images, moving images, graphics, etc. Through DAB, it is possible to provide multimedia services, such as travel and traffic information services, a program linkage information service that provides a news image combined with headline characters or weather forecast and traffic information combined with electronic maps. Enhanced services such as web site broadcasting or a Global Positioning System (GPS) service, and a moving image service may also be provided with DAB.
Audio services, packet mode services, and stream mode data services among such services are provided based on a DAB standard (ETSI EN 300 401). However, video services using the stream mode data services are not defined in the DAB standard. Accordingly, in order to transmit or receive video data, the DAB standard should be corrected or complemented. For that, it is possible to make a standard of defining a transmission method of a broadcasting company and a receiving method of a receiver and provide a video service based on the standard. However, in this case, receivers which do not satisfy such a standard cannot receive the provided video service through a DAB stream mode.
Also, in the case where the video service is provided by a stream mode data service which is a main service channel, a provided video service stream generally includes encoding parameters regarding the video service and information for how the video data is packetized. Therefore, in order to stably receive the video data, the main service channel of DAB must be decoded so that the encoding parameters and the packetization method of the video data can be recognized.